These researchers take an interesting approach to boosting the activity of stem cells so as to effect regeneration, demonstrating their approach in teeth. By the look of it this is effectively a means of induced hormesis, taking advantage of a very general cellular response to mild stress, but in a more controlled way than has been possible in the past:
The team used a low-power laser to trigger human dental stem cells to form dentin, the hard tissue that is similar to bone and makes up the bulk of teeth. What's more, they outlined the precise molecular mechanism involved, and demonstrated its prowess using multiple laboratory and animal models. It turns out that a ubiquitous regulatory cell protein called transforming growth factor beta-1 (TGF-β1) played a pivotal role in triggering the dental stem cells to grow into dentin. TGF-β1 exists in latent form until activated by any number of molecules.
Here is the chemical domino effect the team confirmed: In a dose-dependent manner, the laser first induced reactive oxygen species (ROS), which are chemically active molecules containing oxygen that play an important role in cellular function. The ROS activated the latent TGF-β1 complex which, in turn, differentiated the stem cells into dentin. Nailing down the mechanism was key because it places on firm scientific footing the decades-old pile of anecdotes about low-level light therapy (LLLT), also known as Photobiomodulation (PBM).
Since the dawn of medical laser use in the late 1960s, doctors have been accumulating anecdotal evidence that low-level light therapy can stimulate all kind of biological processes including rejuvenating skin and stimulating hair growth, among others. The clinical effects of low-power lasers have been subtle and largely inconsistent. The new work marks the first time that scientists have gotten to the nub of how low-level laser treatments work on a molecular level, and lays the foundation for controlled treatment protocols.